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result(s) for
"Fernandes, L M P"
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Sustainable Sweeteners: Unveiling Biotechnological Promise of Novel Yeast Strains for Low-Calorie Sweetener Production
by
de Brito de Paula, M. S.
,
Simoes, L. A.
,
Dias, D. R.
in
Agricultural production
,
arabitol
,
Biochemistry
2025
In the food context, people are always looking for alternative ways to substitute highly caloric sugars with sweeteners that have little or no calories. This is an ongoing effort to find new methods for creating sweet-tasting food without the negative health effects that come with consuming too much sugar. This study tested the capacity of 32 yeast strains to produce erythritol, mannitol, and arabitol in a medium containing glycerol or glucose as carbon sources. Two strains of
Yarrowia lipolytica
CCMA 0242 and CCMA 0357 and
Candida rugosa
CCMA 0371 were found to have the greatest capacity to produce erythritol, with yields of 5.19 ± 0.58, 4.60 ± 0.63 and 10.70 ± 0.01 g/L, respectively. The potential of the strains evaluated is promising, especially for
C. rugosa
, a yeast not yet explored for the production of polyols, which produced the highest amounts of erythritol, mannitol, and arabitol, using glycerol as a carbon source, contributing to a fermentative process economically competitive and with a great biotechnological application at the industrial level.
Journal Article
Thiamine deficiency, oxidative metabolic pathways and ethanol-induced neurotoxicity: how poor nutrition contributes to the alcoholic syndrome, as Marchiafava–Bignami disease
2017
Ethanol is an important risk factor for the occurrence of several brain disorders that depend on the amount, period and frequency of its consumption. Chronic use of ethanol often leads to the development of neurodegenerative syndromes, which cause morphological and functional impairments such as foetal alcohol syndrome in newborns exposed to ethanol during pregnancy, Wernicke–Korsakoff Syndrome and, more rarely, Marchiafava–Bignami disease (MBD). MBD is characterized by primary degeneration of the corpus callosum, without inflammation and is associated with oxidative stress and hypovitaminosis, as well as altered mental status, to mention dementia, seizures, depression and so on. This review discusses MBD and poor nutrition as a risk factor for the development of such alcoholic syndrome, with focus on diagnosis, pathogenic aspects, signs and symptoms, as well as therapeutic perspectives. On the basis of the inclusion/exclusion criteria adopted, the performed search in scientific databases (Pubmed, Scielo and Google Scholar) resulted in 100 studies that are being presented and discussed in the present work. Review, case–control and cohort studies on alcoholism-associated hypovitaminosis, oxidative stress, MBD and ethanol metabolism pathways were admitted as relevant. We highlight that MBD is a poorly described, diagnosed, insidious and progressive condition, for which evidence suggests a synergism between ethanol-induced neurotoxic effects and hypovitaminosis B. Present treatment consists of vitamin B1(thiamine) supplementation. Nonetheless, other strategies such as the inclusion of antidepressants or steroidal anti-inflammatories as add-on therapies have been employed as an attempt to improve the damage. Indeed, both the diagnosis and treatment are difficult, and death occurs within few years.
Journal Article
Sensitivity of NEXT-100 to neutrinoless double beta decay
by
Yahlali, N.
,
Lebrun, P.
,
Rodríguez, J.
in
Beta decay
,
Classical and Quantum Gravitation
,
Computer simulation
2016
A
bstract
NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0
νββ
) decay of
136
Xe. The detector possesses two features of great value for 0
νββ
searches: energy resolution better than 1% FWHM at the
Q
value of
136
Xe and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 × 10
−4
counts keV
−1
kg
−1
yr
−1
. Accordingly, the detector will reach a sensitivity to the 0
νββ
-decay half-life of 2.8 × 10
25
years (90% CL) for an exposure of 100 kg·year, or 6.0 × 10
25
years after a run of 3 effective years.
Journal Article
Experiments towards resolving the proton charge radius puzzle
2016
We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from scattering and regular hydrogen spectroscopy.
Journal Article
Sensitivity of a tonne-scale NEXT detector for neutrinoless double-beta decay searches
by
Lebrun, P.
,
Teixeira, J. M. R.
,
Pérez, J.
in
Beta decay
,
Classical and Quantum Gravitation
,
Collaboration
2021
A
bstract
The
Neutrino Experiment with a Xenon TPC
(NEXT) searches for the neutrinoless double-beta (0
νββ
) decay of
136
Xe using high-pressure xenon gas TPCs with electroluminescent amplification. A scaled-up version of this technology with about 1 tonne of enriched xenon could reach in less than 5 years of operation a sensitivity to the half-life of 0
νββ
decay better than 10
27
years, improving the current limits by at least one order of magnitude. This prediction is based on a well-understood background model dominated by radiogenic sources. The detector concept presented here represents a first step on a compelling path towards sensitivity to the parameter space defined by the inverted ordering of neutrino masses, and beyond.
Journal Article
Sensitivity of the NEXT experiment to Xe-124 double electron capture
by
Yahlali, N.
,
Lebrun, P.
,
Haefner, J.
in
Beta decay
,
Classical and Quantum Gravitation
,
Confidence intervals
2021
A
bstract
Double electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature is quite different, potentially providing a new channel to measure the hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino double electron capture (2
νEC EC
) has been predicted for a number of isotopes, but only observed in
78
Kr,
130
Ba and, recently,
124
Xe. The sensitivity to this decay establishes a benchmark for the ultimate experimental goal, namely the potential to discover also the lepton-number-violating neutrinoless version of this process, 0
νEC EC
. Here we report on the current sensitivity of the NEXT-White detector to
124
Xe 2
νEC EC
and on the extrapolation to NEXT-100. Using simulated data for the 2
νEC EC
signal and real data from NEXT-White operated with
124
Xe-depleted gas as background, we define an optimal event selection that maximizes the NEXT-White sensitivity. We estimate that, for NEXT-100 operated with xenon gas isotopically enriched with 1 kg of
124
Xe and for a 5-year run, a sensitivity to the 2
νEC EC
half-life of 6
×
10
22
y (at 90% confidence level) or better can be reached.
Journal Article
The muonic hydrogen Lamb-shift experiment
2005
The charge radius of the proton, the simplest nucleus, is known from electron-scattering experiments only with a surprisingly low precision of about 2%. The poor knowledge of the proton charge radius restricts tests of bound-state quantum electrodynamics (QED) to the precision level of about 6 × 10
6
, although the experimental data themselves (1S Lamb shift in hydrogen) have reached a precision of 2 × 10
6
. The determination of the proton charge radius with an accuracy of 10
3
is the main goal of our experiment, opening a way to check bound-state QED predictions to a level of 10
7
. The principle is to measure the 2S2P energy difference in muonic hydrogen (µ
p) by infrared laser spectroscopy. The first data were taken in the second half of 2003. Muons from our unique very-low-energy muon beam are stopped at a rate of ~100 s
1
in 0.6 mbar H
2
gas where the lifetime of the formed µp(2S) atoms is about 1.3 µs. An incoming muon triggers a pulsed multistage laser system that delivers ~0.2 mJ at λ ≈ 6 µm. Following the laser excitation µp(2S) → µp(2P) we observe the 1.9 keV X-rays from 2P1S transitions using large area avalanche photodiodes. The resonance frequency, and, hence, the Lamb shift and the proton radius, is determined by measuring the intensity of these X-rays as a function of the laser wavelength. A broad range of laser frequencies was scanned in 2003 and the analysis is currently under way.
PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi
Journal Article
Demonstration of background rejection using deep convolutional neural networks in the NEXT experiment
by
Yahlali, N.
,
Lebrun, P.
,
Haefner, J.
in
Artificial neural networks
,
Beta decay
,
Classical and Quantum Gravitation
2021
A
bstract
Convolutional neural networks (CNNs) are widely used state-of-the-art computer vision tools that are becoming increasingly popular in high-energy physics. In this paper, we attempt to understand the potential of CNNs for event classification in the NEXT experiment, which will search for neutrinoless double-beta decay in
136
Xe. To do so, we demonstrate the usage of CNNs for the identification of electron-positron pair production events, which exhibit a topology similar to that of a neutrinoless double-beta decay event. These events were produced in the NEXT-White high-pressure xenon TPC using 2.6 MeV gamma rays from a
228
Th calibration source. We train a network on Monte Carlo-simulated events and show that, by applying on-the-fly data augmentation, the network can be made robust against differences between simulation and data. The use of CNNs offers significant improvement in signal efficiency and background rejection when compared to previous non-CNN-based analyses.
Journal Article
The next generation of laser spectroscopy experiments using light muonic atoms
2018
Precision spectroscopy of light muonic atoms provides unique information about the atomic and nuclear structure of these systems and thus represents a way to access fundamental interactions, properties and constants. One application comprises the determination of absolute nuclear charge radii with unprecedented accuracy from measurements of the 2S - 2P Lamb shift. Here, we review recent results of nuclear charge radii extracted from muonic hydrogen and helium spectroscopy and present experiment proposals to access light muonic atoms with Z ≥ 3. In addition, our approaches towards a precise measurement of the Zemach radii in muonic hydrogen (μp) and helium (μ3He+) are discussed. These results will provide new tests of bound-state quantum-electrodynamics in hydrogen-like systems and can be used as benchmarks for nuclear structure theories.
Journal Article
Laser Excitation of Muonic 1S Hydrogen Hyperfine Transition: Effects of Multi-pass Cell Interference
2026
Calculating the laser-induced transition probability by using the fluence distribution that neglects interference effects (e.g., by employing ray-tracing methods) can lead to an overestimation of this probability, as it underestimates saturation effects. In this paper, we investigate how interference effects in the multi-pass cell, used to enhance the laser fluence, affect the laser-induced transition probability between hyperfine levels in muonic hydrogen, a bound system of a negative muon and a proton. To avoid complications related to the exact knowledge of the intra-cavity field, we develop a simple model that estimates the maximal possible interference effects for given laser and multi-pass cell parameters, thereby providing an upper bound for the resulting decrease in transition probability relative to the case where these effects are neglected. A numerical evaluation of this upper bound for muonic hydrogen shows that, under our experimental conditions, such effects can be safely neglected. Nonetheless, the methodology presented here could be applied to estimate the impact of interference effects on the laser-induced transition probability in other experiments involving coherent light in multi-pass systems.